Programs can be analyzed to determine bounds on the ranges of values assumed by variables at various points in the program. This range information can then be used to eliminate redundant tests, verify correct operation, choose data tepresentations, select code to be generated,. and provide diagnostic Information. Sophisticated analyses involving the proofs of complex assertions are sometimes required to derive accurate range information for the purpose of proving programs correct. The performance of such algorithm5 fay be unacceptable for the routine analysis required during compilation process. This paper presents a discussion of mechanical fange analysis employing techniques practical for use in a cotnpiler. This analysis can also serve as a useful adjunct to the more sophisticated techniques required for program proving. Copyright © 1977 by The Institute, of Electrical and Electronics Engineers, Inc.